Fire Door Frames: The Half of the Assembly Everyone Forgets

What certification says about frames

• Material/section minimums: tested configurations name frame timber (density/species classes) and sections — the doorset route supplies them matched; site assembly must match or evidence equivalents (the doorsets-vs-blanks fork at its sharpest)
• Fixing schedules: frame-to-structure fixings (count, depth, position) per test evidence — loose frames flex gaps open under fire pressure (and under inspection push-tests)
• Stop dimensions: planted vs rebated stops with minimum coverages — the leaf's closing seat being part of the tested geometry
• Frame seals: intumescent positioning sometimes frame-routed (the seals guide's either/or) — replacement frames must rebuild the seal architecture
• The junction: frame-to-wall gaps fire-stopped with tested systems (mineral wool/mastic per the fire-stopping guide's disciplines) — the perimeter joint compartmentation surveys probe behind architraves
• Architraves: decoration concealing the junction — removable, replaceable, evidentially irrelevant (and the survey's access point to the truth behind)

How frames fail doors

The frame failure modes filling remedial schedules: rot at thresholds (mopped floors, external exposure — leaf swings perfectly in a crumbling seat), fixing fatigue (slamming decades working frames loose — the gap drift the tolerance guide measures often lives here, not in hinges), impact damage (trolley/bed strikes splitting stops — care and warehouse contexts per their guides), settlement racking (frames following buildings out of square until tolerance dies), and junction voids (never-stopped perimeter gaps — invisible until surveys lift architraves, then suddenly everyone's compartmentation problem per the passive-fire whole-system view). The verdict consequences: frame failures condemn assemblies whatever the leaf's virtue (the replacement-vs-repair framework's frame test), while frame repairs within scope (sections replaced, re-fixing, junction stopping) rescue assemblies wholesale — the £150–£400 lines that save £1,000 doorsets.

Works, costs and survey attention

Practical frame economics: in-works frame replacement (£150–£400 added to door installation — the cost guide's line item) versus doorset routes (frame included, junction works still real); standalone frame repairs (sections, re-fixing, stop rebuilding) £100–£300 by extent; junction fire-stopping £30–£120 per opening within fire-stopping visit economics (batched with the compartmentation works the same risers always need — the bundling refrain). Survey practice answering the forgetfulness: frames probed not glanced (fixing firmness, rot screwdriver-tests at thresholds, stop integrity), junctions sampled behind architraves where risk indicates (the intrusive option block programmes increasingly buy), and frame verdicts stated per door (the grading outputs distinguishing leaf/frame/assembly fates). The assembly principle closes where it opened: doors are systems — and the system's quiet half deserves half the attention, which is roughly four times what it usually gets.